| 摘要 |
PURPOSE:To prevent a power factor from falling when the speed of a motor is low, by providng a magnetic flux controller which regulates the magnitude of the field flux depending on the speed of the motor to keep the power factor constant in cooperation with a phase advance capacitor. CONSTITUTION:A phase advance capacitor 5, a thyristor power converter 2, a smoothing reactor 3 and a DC motor 4 are connected to an AC power source 1. A field current regulating variable resistor 8 is coupled to the field winding 6 of the motor 4. When a pump or the like whose torque is proportional to the square of the rotational frequency is used as a load, the variable resistor 8 is adjusted to control the field current. As a result, the power factor looking from the power source is not advanced but kept almost constant although the phase advance capacitor 5 is provided. |
